qfe

- SUNW,qfe Quad Fast-Ethernet device driver

Synopsis

/dev/qfe

Description

The SUNW,qfe Quad Fast-Ethernet driver is a multi-threaded, loadable, clonable,
STREAMS hardware driver supporting the connectionless Data Link Provider Interface, dlpi(7P), over
a SUNW,qfe Quad Fast-Ethernet controller. Multiple SUNW,qfe controllers installed within the
system are supported by the driver. The qfe driver provides basic support
for the SUNW,qfe hardware. It is used to handle the SUNW,qfe
device. Functions include chip initialization, frame transit and receive, multicast and promiscuous
support, and error recovery and reporting.

SUNW,qfe

The SUNW,qfe device provides a 100Base-TX networking interface. There are two types
of SUNW,qfe device: one supporting Sbus and the other supporting the
PCI bus interface. The Sbus SUNW,qfe device uses Sun's FEPS ASIC, which
provides the Sbus interface and MAC functions. The PCI SUNW,qfe device
uses Sun's PFEX ASIC to provide the PCI interface and MAC functions. Both
connect with the 100Base-TX on-board transceiver, which connects to a RJ45 connector
to provide the Physical layer functions and external connection.

The 100Base-TX standard specifies an “auto-negotiation” protocol to automatically select the mode
and speed of operation. The internal transceiver is capable of doing auto-negotiation
with the remote-end of the link (link partner) and receives the capabilities
of the remote end. It selects the Highest Common Denominator mode of operation
based on the priorities. It also supports forced-mode of operation where
the driver can select the mode of operation.

APPLICATION PROGRAMMING INTERFACE

The cloning character-special device /dev/qfe is used to access all SUNW,qfe
controllers installed within the system.

qfe and DLPI

The qfe driver is a “style 2” data link service provider.
All M_PROTO and M_PCPROTO type messages are interpreted as DLPI primitives. Valid
DLPI primitives are defined in <sys/dlpi.h>. Refer to dlpi(7P) for more information.
An explicit DL_ATTACH_REQ message by the user is required to associate the
opened stream with a particular device (ppa). The ppa ID is interpreted
as an unsigned long data type and indicates the corresponding device instance (unit)
number. The driver returns an error (DL_ERROR_ACK) if the ppa field value does
not correspond to a valid device instance number for this system. The
device is initialized on first attach and de-initialized (stopped) at last detach.

The values returned by the driver in the DL_INFO_ACK primitive in response
to the DL_INFO_REQ from the user are as follows:

The maximum SDU is 1500 (ETHERMTU - defined in <sys/ethernet.h>).

The minimum SDU is 0.

The dlsap address length is 8.

The MAC type is DL_ETHER.

The sap length values is -2 meaning the physical address component is followed immediately by a 2 byte sap component within the DLSAP address.

The service mode is DL_CLDLS.

No optional quality of service (QOS) support is included at present so the QOS fields are 0.

Once in the DL_ATTACHED state, the user must send a DL_BIND_REQ to
associate a particular service access pointer SAP with the stream. The qfe driver interprets the
sap field within the DL_BIND_REQ as an Ethernet “type” therefore valid values
for the sap field are in the [0-0xFFFF] range. Only one
Ethernet type can be bound to the stream at any time.

If the user selects a sap with a value of 0, the
receiver will be in “802.3 mode”. All frames received from the media
having a “type” field in the range [0-1500] are assumed to be
802.3 frames and are routed up all open streams which are bound to
sap value 0. If more than one stream is in “802.3 mode”
then the frame will be duplicated and routed up multiple streams as
DL_UNITDATA_IND messages.

In transmission, the driver checks the sap field of the DL_BIND_REQ if
the sap value is 0, and if the destination type field is
in the range [0-1500]. If either is true, the driver computes the length
of the message, not including initial M_PROTO mblk (message block), of all subsequent
DL_UNITDATA_REQ messages and transmits 802.3 frames that have this value in the
MAC frame header length field.

The qfe driver DLSAP address format consists of the 6 byte physical
(Ethernet) address component followed immediately by the 2 byte sap (type) component
producing an 8 byte DLSAP address. Applications should not hardcode to this particular
implementation-specific DLSAP address format but use information returned in the DL_INFO_ACK primitive
to compose and decompose DLSAP addresses. The sap length, full DLSAP length,
and sap/physical ordering are included within the DL_INFO_ACK. The physical address length
can be computed by subtracting the sap length from the full DLSAP address
length or by issuing the DL_PHYS_ADDR_REQ to obtain the current physical address
associated with the stream.

Once in the DL_BOUND state, the user may transmit frames on the
Ethernet by sending DL_UNITDATA_REQ messages to the qfe driver. The qfe driver
will route received Ethernet frames up all those open and bound streams having
a sap which matches the Ethernet type as DL_UNITDATA_IND messages. Received
Ethernet frames are duplicated and routed up multiple open streams if necessary.
The DLSAP address contained within the DL_UNITDATA_REQ and DL_UNITDATA_IND messages consists of
both the sap (type) and physical (Ethernet) components.

In addition to the mandatory connectionless DLPI message set the driver also
supports the following primitives.

qfe Primitives

The DL_ENABMULTI_REQ and DL_DISABMULTI_REQ primitives enable or disable reception of individual multicast
group addresses. A set of multicast addresses may be iteratively created and
modified on a per-stream basis using these primitives. The driver accepts these
primitives in any state following DL_ATTACHED.

The DL_PROMISCON_REQ and DL_PROMISCOFF_REQ primitives with the DL_PROMISC_PHYS flag set in the
dl_level field enables or disables reception of all frames on the media
(“promiscuous mode”), including frames generated by the local host.

When used with the DL_PROMISC_SAP flag set this enables or disables reception
of all sap (Ethernet type) values. When used with the DL_PROMISC_MULTI flag
set this enables or disables reception of all multicast group addresses. The effect
of each is always on a per-stream basis and independent of the
other sap and physical level configurations on this stream or other streams.

The DL_PHYS_ADDR_REQ primitive returns the 6 octet Ethernet address currently associated (attached)
to the stream in the DL_PHYS_ADDR_ACK primitive. This primitive is valid
only in states following a successful DL_ATTACH_REQ.

The DL_SET_PHYS_ADDR_REQ primitive changes the 6 octet Ethernet address currently associated (attached)
to this stream. The credentials of the process which originally opened this
stream must be root. Otherwise EPERM is returned in the DL_ERROR_ACK. This
primitive is destructive in that it affects all other current and future
streams attached to this device. An M_ERROR is sent up all other
streams attached to this device when this primitive is successful on this stream.
Once changed, all streams subsequently opened and attached to this device
will obtain this new physical address. Once changed, the physical address
will remain until this primitive is used to change the physical address
again or the system is rebooted, whichever comes first.

qfe Driver

By default, the qfe driver performs “auto-negotiation” to select the
mode and speed of the link.

The link can be in one of the four following modes:

100 Mbps, full-duplex

100 Mbps, half-duplex

10 Mbps, full-duplex

10 Mbps, half-duplex

These speeds and modes are described in the 100Base-TX standard.

The auto-negotiation protocol automatically selects:

Operation mode (half-duplex or full-duplex)

Speed (100 Mbps or 10 Mbps)

The auto-negotiation protocol does the following:

Gets all the modes of operation supported by the Link Partner

Advertises its capabilities to the Link Partner

Selects the highest common denominator mode of operation based on the priorities.

The highest priority is given to the 100 Mbps, full-duplex; lowest priority is given to 10 Mbps, half-duplex.

The 100Base-TXtransceiver is capable of all of the operating speeds and
modes listed above. By default, auto-negotiation is used to select the speed
and the mode of the link and the common mode of operation
with the link partner.

Sometimes, the user may want to select the speed and mode of
the link. The SUNW,qfe device supports programmable "IPG" (Inter-Packet Gap) parameters
ipg1 and ipg2. By default, the driver sets ipg1 to 8
byte-times and ipg2 to 4 byte-times (which are the standard values).
Sometimes, the user may want to alter these values depending on whether
the driver supports 10 Mbps or 100 Mpbs and accordingly, IPG will
be set to 9.6 or 0.96 microseconds.

qfe Parameter List

The qfe driver provides for setting and getting various parameters for the
SUNW,qfe device. The parameter list includes:

current transceiver status

current link status

inter-packet gap

local transceiver capabilities

link partner capabilities

The local transceiver has two sets of capabilities: one set reflects the
capabilities of the hardware, which are read-only (RO) parameters, and the
second set, which reflects the values chosen by the user, is
used in speed selection. There are read/write (RW) capabilities. At boot
time, these two sets of capabilities will be the same. The Link Partner
capabilities are also read-only parameters because the current default value of these
parameters can only be read and cannot be modified.